1. Field of the Invention
The present invention relates to novel herbicidal phenoxypropionic acid N-alkyl-N-2-fluorophenyl amide compounds represented in the following formula (1), a method for preparing thereof, their use to control barnyard grass produced from rice and composition as suitable herbicides. 
wherein,
R is methyl or ethyl group;
X is hydrogen, halogen, cyano, C1xcx9cC6 alkyl, C1xcx9cC6 alkoxy, C1xcx9cC3 haloalkyl substituted with 1 to 3 of halogen atom(s), C1xcx9cC3 haloalkoxy substituted with 1 to 3 of halogen atom(s), C2xcx9cC4 alkoxyalkoxy, phenoxy, benzyloxy, C2xcx9cC6 alkenyl, C2xcx9cC6 alkinyl, C2xcx9cC6 alkenyloxy, C2xcx9cC6 alkinyloxy, or phenyl group;
Y is hydrogen or fluoro;
n is an integer of 1 or 2 and when n is 2, X can be in a combination of other substituents.
2. Description of the Prior Art
U.S. Pat. No. 4,130,413 discloses the compound containing the following formula (2). 
wherein, (R1)m is hydrogen, halogen, CF3, NO2, CN or alkyl group; A is O, S or NH; R2 is hydrogen or alkyl group; Z is 
where R3 and R4, that are the same or different, are hydrogen, C1xcx9cC6 alkyl, C3xcx9cC6 hydroxyalkyl, C3xcx9cC6 cycloalkyl, C1xcx9cC4 alkoxy, or phenyl substituted where 1 to 3 substituents are selected from C1xcx9cC4 alkyl group, C1xcx9cC6 alkoxy group, halogen and CF3 
U.S. Pat. No. 4,531,969 discloses the compounds containing the following formula (3). 
wherein, R5 is 
where R6 is hydrogen or halogen atom, R7 is hydrogen or alkyl group); Z is the same as defined above.
U.S. Pat. No. 5,254,527 discloses the compounds containing the following formula (4). 
wherein, R5 and Z are the same as defined above.
None of the patents teaches the synthesis of the compound represented in the above formula (1) and have tested the same for herbicidal activity.
JP Patent publication 2-11580 discloses the compound represented in the following formula (5). 
wherein, L is lower alkyl, halogen, methoxy, methoxyphenoxy, methylthio or methylvinyl group; n is an integer of 0 to 2.
JP Patent publication sho 53-40767 and sho 54-112828 also disclose that phenoxypropionic acid amide derivatives have herbicidal activity.
However, none of reports including the patents mentioned above has taught a method for preparing the compounds in the above formula (1) and tested the same against herbicidal activity. And also it has not been reported that the compounds have superior herbicidal activity and selectivity toward rice and control barnyard grass produced from rice.
Even though many of herbicides for rice have been recently developed and used, barnyard grass among weeds is the biggest problem in rice paddy.
Development of herbicides to control barnyard grass is an urgent to one who is in the field of agriculture. After transplanting young rice, herbicides, developed until now, cannot effectively control the production of barnyard grass so that it causes a huge damage to harvest. It has been reported that when barnyard grass is produced for one week in 1 m2, amount of harvest decreases by 2%, for 5 weeks by about 10%, for 10 weeks by 19% and for 20 weeks by 35%.
Many herbicides have been used for the purpose of controlling barnyard grass that damages in amount of harvest of rice. However, the herbicide with a broader herbicidal activity, environmentally-friendly property and cost-effectiveness is still in demand.
The inventors have intensively studied to prepare herbicides to effectively control barnyard grass. As a result, they completed this invention to find a novel phenoxypropionic acid N-alkyl-N-2-fluorophenyl amide and its derivatives that are stable to rice and selectively control barnyard grass. This superior effectiveness is distinguished from the conventional inventions.
The present invention is characterized by novel phenoxypropionic acid N-alkyl-N-2-fluorophenyl amide represented in the following formula (1) with an excellent herbicidal activity as well as selectively stable toward rice. 
wherein, R, X, Y and n are the same as previously defined.
The compounds of the formula (1) according to the present invention may be specified as the following Table 1.
The compounds of formula (1) according to this invention can be synthesized by a conventional method represented in the following scheme 1, reacting a compound of the formula (6) with a compound of the formula (7). 
wherein, Xxe2x80x2 is OH, Cl, Br or phenoxy group; R, X, Y and n are the same as previously defined.
In the method according to scheme 1, it is prefer to use a binder such as triphenylphosphine and an organic base such as triethylamine or pyridine by keeping temperature at 0xcx9c100xc2x0 C. in an inert solvent such as ethers like tetrahydrofuran, ethyethyl acetate, acetonitrile, toluene, xylene, hexane, methylene chloride, carbon tetrachloride, dichloroethane or the like, and to purify the crude product by column chromatography.
Another method for preparing the compounds (1) represented in the following scheme 2 is an alkylation of a compound of the formula (8) to compounds of the formula (9). 
wherein, Xxe2x80x3, which is a leaving group, is Cl, Br, I, benzenesulfonyloxy, toluenesulfonyloxy, methanesulfonyloxy or lower alkyl sulfate group; R, X, Y and n are the same as previously defined.
In scheme 2, it is prefer to use a strong base which is enough to pull out a hydrogen from amide, NH. The strong base used in this invention is NaOH, KOH, LiOH, NaH, n-BuLi or LDA. It is prefer to carry this reaction at the temperature of xe2x88x9278xcx9c50xc2x0 C. in an inert solvent such as ethers like ethylether, dioxane or tetrahydrofuran or hydrocarbons like hexane.
Another method for preparing the compounds (1) represented in the following scheme 3 is a reaction of a compound of the formula (10) with a compound of the formula (11) in the presence of a base. 
wherein, Yxe2x80x2 is halogen, alkylsulfonyloxy, haloalkylsulfonyloxy, benzenesulfonyloxy or toluenesulfonyloxy group; R, X, Y, and n are the same as previously defined.
In Scheme 3, it is prefer to use inorganic bases such as alkali metal hydroxides like sodium hydroxide or potassium hydroxide, alkali metal carbonates like sodium carbonate or potassium carbonate, alkali metal hydrogencarbonates like sodium hydrogencarbonate or potassium hydrogencarbonate or organic bases like triethylamine, N,N-dimethylaniline, pyridine or 1,8-diazabicyclo[5,4,0]undec-7-ene.
A phase transition catalyst such as tetra-n-butylammonium bromide or 18-crown-6-[1,4,7,10,13,16-hexaoctacyclooctadecane] can be added to complete a reaction rapidly, if necessary. And also one or more than two solvents can be combined and used, if deemed necessary. It is prefer to use an inert organic solvent; for example; ketones such as acetone; aromatic hydrocarbons such as toluene, xylene or chlorobenzene; aliphatic hydrocarbons such as petroleum ether or ligroin; ethers such as diethylether, tetrahydrofuran or dioxane; nitrites such as acetonitrile or propionitrile; or amides such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone. A reaction is carried at the temperature of from 0xc2x0 C. to reflux, preferably 5xcx9c50xc2x0 C. for 1 to 24 hour(s) to afford a high yield.
Another method for preparing the compound (1) represented in the following scheme 4 is a reaction of a compound of the formula (12) with a compound of the formula (13) in the presence of a base. 
wherein, X, Y, Yxe2x80x2, R and n are the same as previously defined.
In Scheme 4, it is prefer to use inorganic bases; for example; alkali metal hydroxides such as sodium hydroxide or potassium hydroxide, alkali metal carbonates such as sodium carbonate or potassium carbonate, alkali metal hydrogencarbonates such as sodium hydrogencarbonate or potassium hydrogencarbonate or organic bases such as triethylamine, N,N-dimethylaniline, pyridine, picoline, quinoline, or 1,8-diazabicyclo[5,4,0]undec-7-ene.
A phase transition catalyst such as tetra-n-butylammonium bromide or 18-crown-6[1,4,7,10,13,16-hexaoctacyclooctadecane] can be used, if necessary. And also one or more than two solvents can be combined and used if deemed necessary. It is prefer to use an inert organic solvent; for example; ketones such as acetone or butanone; aromatic hydrocarbons such as benzene, toluene, xylene or chlorobenzene; aliphatic hydrocarbons such as petroleum ether, or ligroin; ethers such as diethylether, tetrahydrofuran or dioxane; nitriles such as acetonitrile or propionitrile; or amides such as N,N-dimethylformamide, N,N-dimethyl acetamide or N-methylpyrrolidone. A reaction is carried at the temperature of from0xc2x0 C. to reflux, preferably 20xcx9c100xc2x0 C. for 1 to 24 hour(s) to afford a high yield.